Air conditioning system



Dec. 29, 1942. A, B NEWTQN AIR CONDITIONING SYSTEM 3 Sheets-Sheet l Filed July 26, 1939 nun/I "la/11111111111.w.v11111/11111/lill/111111111111111 fnventor Alwin B'. New-iron.

Dec. 29,1942. [AaNEwTON 2,306,463

AIR CONDITIONING s-Y'sTEM Filed July ze, l1959 5 sheets-sheet 2 v/m f .2 o we v l lma 11| |69 |10 I /fll k Jj Le) A @I Mez Fig. 3

' fhwenfor Alwin B. Newon.

Dec- 29, 1942- A; B. NEWTON AIR CONDITIONING SYSTEM Filed July 26, 1939 3 Sheets-bnee:l E

.f2s ff CONDENSER Fig/a CONDENSER Gemes lhaten-ted Dec. 29, 1942 `unirsi) STATE s ParrENT orifice 2.30am l an: coNnrrroNn'va srsrsn Alwin B. Newton, Minneapolis. Minn., assignor to Minneapolis-Honeywell Regulator Company. Minneapolis, Minn., a corporation or Delaware Application July 26. 1939, Serial Hmmm .14 Cllliilis.4 (Cl. 8M)

- let and outlet portions of the evaporator, and

controlling the relative eil'ectiveness of the connections so that the operating bellows or diaphragm of the valve may respond to the pressure at the evaporator inlet or at the evaporator outlet, or to some intermediate pressure, .and

orator is relatively small.

In accordance with the teachings of the present invention, it is possible to modulate the coil from '0% to-100%fcoil capacity, even in thosecasesywhere the pressure drop through thel evap- It is accordingly an lobiect of ventionto provide a novel arrangement for con trolling the effective cooling surface of an evaporator coil of a direct expansion refrigeration system.

More specifically,` it is an object or the presv v ent invention to provide a novel arrangement lfor modulating the capacity of an evaporator coil of a direct expansion refrigeration system between 100% and 0%.

Another object of the present invention is the provision of a self contained valve and operatin this manner the cooling capacity of the evaporator may be readily adjusted in accordance with some condition to be controlled, such as the temperature of a space. The reason why the capacity of an evaporator may be controlled in this manner is because of the drop in pressure through the evaporator, so that if the operating member for the expansion valve responds to the relatively low pressure at the evaporator outlet, a smaller rise in temperature is necessary to cause the valve to open than when the operating member responds to the higher pressure at the evaporator inlet, so that, for a given evaporator pressure. if the valve operating bellows or diaphragm responds to the higher inlet pressure. the valve will-not open until -the temperature at the evaporator outlet rises to a vhigher value than when the valve operating bellows. or diaphragm responds tothe lower pressure existing at Athe evaporator outlet.v Accordingly. a

greater portion of the evaporator willfcontain superheated refrigerant when the pressure connection is'taken at the evaporator-inlet than when it is taken at the evaporator outlet. Theretore, by varying the relative eiectiveness of the two pressureconnections, rliirerentv portions of the evaporator will contain superheated refrigerant, and the effective cooling area ofthe evaporator may be readily controlled.

While the'system of this copending application is entirely satisfactory in many applications, it may not be suitable wherethe pressure vdrop thro'ughthe evaporator coil is relatively small, sincefthe success of the system shown-in this copending application is dependent upon the existence of a substantial pressure drop through; the evaporator coil. Furthermore, in

this earlier system, modulation of the evaporator coil 'is usually limited between 100% of coil capacity and about 60%l of coil capacity. In manying means therefor to beapplied to the equalizer connection between the expansion valve and evaporator coil of a direct expansion refrigeration system or in some other suitable location, whereby automatic control of the eilective cooling area of the evaporator between 100% and 0% capacity may be secured.

Other objects and advantages will become apparent upon reference to the specification claims and appended drawings wherein like reference characters represent like parts in the various.

views and wherein Figure 1 is a view showing one form of control system embodying this invention. many o! the parts 'being shown in cross-section and the control system vbeing applied to an evaporator `for use in an air conditioning system,

Figure 2- isa view showing'anl electric motor drive for the control valve of Figure 1,

Figure 3 isaviewsimilartol'igure3butshowing a pneumatic operator for the control valve of Figure l, and

Figures 4 and 5, are schematic views showing modiilcations or the control arrangement o! Figure 1. Referring now to Figure i. the invention is illustratedasbeingappliedtoanevaporator Il oi'a. unit air conditioner Ii although it will be that the principles oftheinventionarenot limitd to this particular application. The air conditioner Il includesacasing I2 havingfl'hllr'inlat Il applications', it is desirable to modulate the evaporator coilbetween andj 0% coil caandreturn air inlet illocatedadiacentthebottom portion thereof. a fan il being provided tor'drawing air through theair conditioner ii bywayoi theinletsita'nd il and discharginglthe air into the space to b'econditionedbywayoftheexhauat outlet it. j Adamper i1 isprovided iorcontrolling the relative amounts of fresh and return air admitted totheairconditionenthisdamperbdng either manually continued or continued automatically -by any suitable means. Located in the Apath ofairfrom theinlets ilandiltothei'an il isthe evaporator il of a the the present in- I wit..

air in passing over this evaporator having its temperature reduced thereby.

The refrigeration system includes a compressor 20 driven by a motor 2|, the high pressure side of the compressor being connected by means of a pipe 22 to the condenser 23, the outlet of the condenser being connected by means o f pipes 24 and 25 to the inlet of a thermostatic expansion valve 26 which may be of any conventional construction, the low pressure side of which valve communicates by means of pipe 21 with the inlet of the evaporator I 0. The outlet of the evaporator communicates by means of the pipe 28 with the inlet of the compressor 20.

The thermostatic expansion valve 26 may any suitable construction and is shown to comprise a valve element 3|! cooperating with a valve seat 3|, the valve element 30 being connected by means of the stem 32 with an operating diaphragm 33. The valve stem 32 may carry a suitable spring retainer 35 against which the compression spring 36 acts to bias the valve element towards closed position. Suitable packing 31 may be provided around the valve stem 32 to reduce leakage of refrigerant thereby. The diaphragm' 33 has a chamber formed above the same by means of the cover member 38 and this space above the diaphragm is connected by meansl of the capillary tube 39 to the bulb, which tube and bulb may be provided with a suitablevolatile ll so that variations in temperature to which the bulb 48 rebe ofy sponds will cause varying pressures to act down-f wardly on the diaphragm 33. The bulb 48 is positioned in intimate engagement withv the outlet portion of the evaporator I8 so that the pressure applied to the upper side of the diaphragm 33 will vary in accordance with variations in tern-` perature of the refrigerant leaving the evaporator lli. The pressure in the space below the diaphragm 33 may be that of the refrigerant adjacent the outlet portion of the evaporator or some higher pressure depending upon the setting of the control device to be hereinafter explained.

This control device is illustrated generally by the reference character 42 and comprises a valve assembly 43 and an operating mechanism 44 which is shown to be mounted by means of a mounting bracket 45 on va suitable panel board 46. .The

valve assembly 43 comprises a valve casing 48 into the lower portion of which is removably secured a valve seat 43 with which cooperates the valve element 53 carried by the rod 5| extending upwardly through the valve body and being guided by means of the member 52 which is screwthreadedly received into the upper portion of the valve body and is held against the lower wall of the casing of the operating mechanism 44 by means .of a nut 63. A suitable washer 54 may be provided between the valve body 48 and the member 52 to prevent leakage of refrigerant betweenthese members from the interior of the valve body 48. A sealing bellows 561s suitably secured Y to the upper portionof the member 52 and to the upper end of the valve stem 5| to prevent leakage of refrigerant from the interior of the valve body by way of the member 62.

Screw-threadedly received by the lower end of the valve body 48 is a fitting 60 having -an inlet 6| communicating by means of the passage 62 with the underside of the valve Aelement 58. The lower end of this tting 6|!` has a member 64 threaded into the lower portion thereof, which member is provided with a suitable inlet opening 55 which communicates by way of the passage 66 and an orice 61 with the passageway 6.2. The orifice 61 may be screw-threaded into the fitting 68 as illustrated so that an orice of any desired size may be inserted therein. Suitably held between the member 64 and the fitting 60 is a strainer 16 which, as shown, is readily movable for purposes of cleaning and prevents any dirt particles from entering the oriilce 61 which might tend to clog the same.

The inlet el or the valveassembly 43 is connected by means of the pipe 12`with the space below the diaphragm 33 of the thermostatic eX- pansion valve and the inlet 65 is connected by means of the pipes 13 and 25 with the high pressure side of the expanion valve. The outlet 15l of the valve assembly 43 is connected by means of a pipe 16 and the pipe 11 to the outlet portion of the evaporator I8, there also being a connection 18 between the pipe 16 and a portion of the evaporator I3 spaced somewhat from the outlet of the evaporator, the connection through the pipes 11 and 18 being under the control of a manually operated three-way valve for a purpose to be later described. v

Located in the return air inlet I4 is a bulb 8| connected by means of a capillary tube 82 with a bellows 83 which is suitably secured to the lower portion of the casing, this tube, bulb and bellows being provided with aA suitable volatile ll whereby the bellows 83 will expand or cbntract in accordance with variations in the return air temperature. While the bulb 8| is illustrated as being located in the return air duct, it should -be understood that if desired this bulb may be located any place within the space being conditioned. Suitably connected to the bellows 83 is -a plunger 84 for controlling the position of a lever pivoted about the knife edge 86 which may be carried by the bracket 81, the right-hand end of this lever having a bearing member 88 which bears against the upper end of the valve stem 5|. The left end of the member 85 moves between stops 30 and 3| which may be carried bythe side wall of the casing 44 and which serve to limit the movement 'of the lever 85 about the pivot 86. The right end of the lever 85 is biased upwardly by means of the tension spring 32 having one end connected to the upturned end 33 of the lever 85 and the other end looped through the adjustable bracket member 35. It will be apparent from the description thus far that as the temperature of the space or in other words, the temperature of the air entering the return air ductincreases, the bellows 83 will expand moving the plunger 84 upwardiyiwhich will cause movement of the lever 85 about the pivot 86 in opposition to the spring 32 so as to y urge the valve stem 5| downwardly to move the of the knife edge |33 forming an extremity of the member |64 suitably ilxed to the inner side wall of the casing 44. Adjacent the connection' between the spring l36 and the lever |8| is a thrust member |85 which terminates in suitable knife edges and rests in the depression |06 in the lever |0| and the depression |01 formed in the bracket |68 suitably secured to the lever 86.

ating mechanism 44.

the lever 85 in a direction to move the valve element 50 downwardly away from the seat 49, the upper end of the .thrust member will be carried to the left by reason 'of the movement of the bracket |08 carried by the lever 85, so that tthe pivot points of the member |05 are no longer in line with the knife edge pivot 88 and the force of the spring 95 is now effective to assist the bellows 83 in moving the left end of the lever 85 upwardly. The further that the left end of the lever 85 is moved upwardly, the further the upper end ofthe member |05 will be moved toward the left so as to increase the eiective moment arm loi.' 'the spring 98 so that this will exert aconascuas 3 outer end an operating knob ||8 which may carry a pointer for cooperation with suitable indicia which may be suitably mounted on' the,

inturned portions |2| which may loosely straddle the bolt II5 and which bear against the nut by reason of the biasing effect exerted on the member 95 by the spring 92. If the knob I I5 is'turned in a direction so as tomove the nut |20 toward the left, the member 95 will pivot uptinuously increasing force on the lever 85 in op- I position to the biasing eilect of the spring 92. The sealing bellows 55 will have a certain spring y rate so as this bellows is gradually compressed a gradually increasing force is required to further compress the same. The spring 98 by reason of the .action aforedescribed is thus eiective in compensating for the spring rate of the bellows 55. As the valve 50 opens, a gradually increasing refrigerant pressure will be appliedto the interior of the bellows 55,' and the spring 95 is eective in compensating for this increasing resistance to the opening movement of the valve. The spring 92 which biases the right end of the'lever 85 upwardly is preferably a relatively stiff spring so that a slight movement of the supporting member 95 will be effective in causing a substantial adjustment of the control range of the oper- However, if the spring 95 were not employed it would require a very substantial temperature change at the bulb 8| to cause the movement of the valve 50 between open and closed positions so that the-operating differential of the apparatus would be veryhigh..

It is desirable however that this operating-differential be relatively low such as 2 or 2% and since the spring 98 assists in the opening movement of the valve element 50, a relatively strong spring 92 may be employed so that ad- 'justment of the control Apoint of the apparatus may be effected by a slight change in position in cross-section, the depth of the U progressively decreasing from the left end to the right, Ias illustrated, the-side walls of the member 95 at the left end thereof being suitably recessed at I I0 and carried by these recesses is a' member III terminating in a knife edge ||2 which knife edge portion iits into the V slot I'I8 of the 'member |04.` This knife edge forms a pivotal support for the member 95. An adjustingscrew ||5 journllnedin the panel board has 'amxed to its wardly about theknife edge pivot ||2l which will have the effect of moving the upper portion of the spring 92 upwardly to increase the tension thereof. Conversely, upon movement of the knob f IIE in the opposite direction, the nut |20 will move toward the right thus permitting the right end of the supporting member 95 to drop downwardly and reducing the force`exerted by the spring 92. By reason of the long lever arm between the pivot ||2 and the right end of the member 95, a large movement may be imparted thereto with -a slight movement of the knob ||8. This knob -||5 and the mechanismv operated thereby forms an adjusting means whereby the temperature setting of the operating mechanism 42 may-be adjusted. Thus upon an increase in the tension of the spring 92 a greater force will be required of the bellows 93 to move the valve element `50 downwardly so that in this manner the temperature setting of the device is increased.

, The cams are so arranged that as they are moved in a counter-clockwise direction, the switch |29 will' first moveto open position and upon further movement in the same direction the switch |28 will move to open position. The switchl |28 controls tl're operationof the-fan I5, the circuit to this fan being as follows: from the line wire -LI' throughconductor |82, switch |28, conductora. |33, the fan motor I5, and conductor |35 tothe line wire L2. The switch 29 controls the circuit -to' the compressormotor 2|, this circuit being as follows: from the line wire LI through conductorl |36, Aswitch |29.' conductor |91, control device |88, conductor |89, compressor .motor |2| and conductor |40 to the line wire L2. Accordingly, when the two mercury switches are in the positions illustrated the fan I5 will be operating and the compressor 2l will operate under the control of the control device |88 to be described. vIf the knob is rotated so as to open the circuit through the switch |29, the fan I5 only will op erate, since the circuit to. the compressor motor has been interrupted. If both switches are opened, the entire system will .of course shut down.

The control device |88 may be of any suitable construction and may comprise a high pres- These switches may be connected in series so that when either the high pressure exceeds a desired value or the suction pressure drops below adesired value the 'compressor will be shut 4 y l down. This control also may be of the type shown and described in application Serial No.

|I is operating and the compressor 20 is under the control of the controller |38. With the parts in the positions illustrated, it is assumed that the temperature of the air in the space, or the airv entering the return air duct is at a suiciently l low value so that the bellows 83 is contracted 'and the lever 85 is in the position illustrated whereby the valve 50 is maintained in closed position by reason of the spring eiect of the bellows 56 and also by reason of the pressure of the refrigerant which leaks into the bellows around the valve stem 5|. If necessary, a spring can be positioned within the bellows 56 to insure that the valve element 50 will remain in closed position at this time although under normal conditions such a spring is unnecessary. With the valve element 50 closed, the connection between the evaporator outlet and thespace below the diaphragm 33 of the expansion valve is shut olf and the liquid refrigerant from the high pressure side of the valve which passes into the space below the diaphragm 33 by way of the orifice B1 will cause a pressure tobuild up below this diaphragm which will be' sufficient to maintain the expansionvalve in tightly closed position. Since there is leakage between the space below the diaphragm 33 and the pipe 21 leading to the evaporator, the pressure below the diaphragm will not build up to an excessive amount so that danger of rupture of the diaphragm is prevented. With the expansion valve held in its tightly closed position at this time, no refrigerant will pass into the evaporator with the exception of that small amount which passes thereto around the stem of the expansion valve and accordingly the compressor will very quickly shut down since the suction pressure switch will open almost immediately after the expansion valve has been tightly closed. If desired.. a separate switch might be evaporator outlet because at this time the leakage of liquid refrigerant into the space below the diaphragm and of the refrigerant around the stem of the expansion valve will be negligible, because of the small size of the passageways between the liquid line and the space below the diaphragm and around the expansion valve stem, as compared to the passageway through the pipes 16 and 11. Accordingly, with the valve 50 wide open, the expansion valve will respond to the temperature of the refrigerant leaving the evaporator and to the pressure of the refrigerant leavingthe evaporator, or in other words, to the superheat of the refrigerant leaving the evaporator. As the valve gradually moves towards closed position in response. to adrop in the space temperature the pressure below the diaphragm 33 will be some pressure intermediate the pressure at the evaporator outlet and the liquid line pressure depending upon how widely open the valve 50 is. As the pressure below the diaphragm increases due to the closing movement of the valve 50, it will require a higher temperature of the refrigerant leaving the evaporator in order to open the expansion valve with the result that an increasingly greater portion thereof will contain superheated refrigerant as the valve 50 is moved towards closed position, until when entirely closedthe` expansion valve will entirely cut off the flow of refrigerant through the evaporator since the temperature at vthe bulb l0 will not normally rise high enough to cause opening movement of the expansion valve at this time. Thus as the space temperature increases, the expansion valve is operated in such a manner that a lesser portion 'of the evaporator contains superheated refrigerant so that the effective cooling surface of the evaporator will increase asthe Y space temperature increases and conversely will placed in the compressor circuit, this switch being arranged to open when the valve element 5l lmoves to closed position. so as to shut the com- -pressor down at this time and prevent any recycling thereof as long as valve 50 is closed.

If n owthe temperature yin the space starts to increase. expansion of the bellows 83 will take y place which will result in movement of the lever 85 in a. direction to start opening the valve member 5Fl and provide communication between the outlet portion of the evaporator Iii andthe space below the diaphragm 33 of the expansion valve. As this valve starts to openthe pressure below the diaphragm 33will decrease and the expansion valve will then be under the control of the bulb .decrease in accordance with the decrease in the leaving the evaporator so that the entire surface thereof is available for cooling an'd intermediate these temperatures a smaller portion of the evaporator will-contain liquid refrigerant depending upon the space temperature. By manipulation of the adjusting knob IIB theactual temperature "which ismaintained by the apparatus'may be effectively controlled as previously descrid.

In some cases it may be that suiiicient liquid refrigerant will ow through the connection 16A and 11 when the valve member 5!! is open so that all of this liquid refrigerant will not be evapy orated and may passto the compressor. In such Thus if the temperature of the space has risen suiliciently so that the valve member 50 is wide open, the pressure below the diaphragm 33 will be substantially that of the refrigerant at the a case it will be desirable to connect the pipe 16 to the evaporator by way of the connection 18 so that there will be suilicient opportunity for this liquid refrigerant to evaporate in the evaporator -and in such a case the valve 8l will be manipufrom to insure.- the evaporation of the small amount of liquid` refrigerant that will pass theretttymtitntplptninetnttrlsttuqnt distributor is provided between the evaporator power imlt ss in mure l. with an electric motor driveas in Figure 2 or a pneumatic motor drive as infFlgure 3 without making any changes whata fitting which encloses the bellows I3 is t screw-threadedly secured to the upper portion of the valve assembly andv clamps between it and the valve assembly, a bracket member |3| to which may be suitably secured as by the ears |32 and bolts |33, a motor |34 which motor may be a proportioning motor 'of the type illustrated in PatentY No. 2,028,110, issued to D. G. Taylor on January 14, 1936. This motor may include a shalt |33 passing through an opening |33 in the bracket member VISI, this shaft carrying adjacent its outel end a cam |31 which acts upon an ad.'

instable screw |63 threaded into a member |30 which is adapted to slide within the opening |13 .in the upper portion of the iltting |30. To prevent rotation of the member |33, it may be slotted as at I'II and a bolt |13 threaded through the side of the tting |60 may pass into the slot Ill so as to permit vertical reciprocation of the mem- Aber |63 but to prevent'rotation thereof. By ad- -justing the screw |33.in the member |60 the position of the valve member may be suitably adjusted for any position of the cam |31. It will now be apparent thatthe same valve assembly 43 shown in Figure 1 is readily adaptable for use with an electric motor drive without any alteration of the valve assembly itself and it will be understood that the driving motor |34 may be operated by a control potentiometer as disclosed in the aforementioned Taylor patent, wlllch control potentiometer may be controlled by space temperature, or if desired, by'space relative humidity or both.

' with Figure il. This motor is shown to ne cuntrollen oy a thermostat sus responding to the.

ever in the valve assembly itself. While these figures illustrate preferred arrangements for connecting` the valve to the various power units it should be understood that they are susceptible of v many modincations.

Referring now to Flgure'4, a modification of the system shown in Figure 1 is illustrated. In this ligure the v alveassembly 43 controls the ilow of refrigerant through the pipe 'IB .to the evaporator I0 as in Figure 1 so'that when the valve element 33 of the valve assembly 43 is entirely open, the pressure below the operating diaphragm of the expansion valve will be that of the refrigerant leaving the evaporator; Positioned in the pipe 13 which connects the yhigh pressure side of the expansioii valveto the opening 65 of the valve 43 is a valve 200 which may be electrically or otherwise controlled such as by a solenoid all, the arrangement being such that when the solenoid is deenergized the valve Zim is in closed position out upon energlzation of the solenoid the valve moves to open position.

The valve. is shown to be operated in this gure by means oiy a proportioning motor zal".

which may beof the. construction shown in the afol'ementionediaylor patent and wllicn ln actual practice may be mounted on thevalve assenibiy4 iii the .manner descrlned in connection temperature oi the space ylieing conditioned and which thermostat may ne ol any suitable construction and may comprise a nulietalilc element 206 controlling tile position oi an arm sul with respeci U0 13818081166 205, me l'm Zul and H18 v resistance N8 ioriliing the control potentiometer Referring n'ow to Figure 3 the valve assembly v 43 is shown connected to a pneumatic motor -for controlling the position of the same. A iitting |15 is provided in place of the fitting |30 and the upper'portion of this fitting has'a peripheral groove |13 igor receiving a set screw |11 screwthreaded in the collar |13. which collar is cony nected by means of arms |13 to a bellows housing |00. Located within the housing |30 is a bellows |3| of any suitable construction and this bellows l controls the position of a thrust member |32 in a manner well known inthe art and which thurst member passes downwardly through an opening |33 in the-top of the' tting |13 and abuts the up-N per end'of the operating bellows 33 of the valve 4,3. A bridge member |33 rests on the collar |13 and supports 'a compression spring |33, the upper end of whichl is in engagement with a collar |31 of the bellows assembly for biasing the bellows 4to collapsed position and for biasing the thrust member |32 upwardly.. pipe |33 connectstotheinthat as the temperature of the space increases -thspressurewitliinthebellowslwillincrease adaptable :or ujwitii mei: stemma tliebollows I3'I and this pipe may be into a pneumatic control system in a manner well fknown in the art, in such amanner evaporator is effective for cooling purposes as 'Y for the motor Zilli. with me tneimostat in the position illustrated it is assumed that the room tempel-aulne is excessive and the motor zu manitains the valve 43 in open 'position by means of the cam 2li operated by me motor. nt this time the expansion valve operates in accordance witnthe superheat of the ren-igei'ant leaving the evaporator. If the space temperature starts to fall, the motor 332 will cause rotation or the cam 2|3 and the valve s3 will operate to cut down theflow through the pipe lesotnatatthistime.

the diaphragm will not respond to the pressure at the evaporator outlet but to some pressure intermediate thisipi'essure and tde pressure in the inletof the evaporator. It should ne understood at this time that, as in Figure i, there will be a certain amount of leakage from the low pressure side of the expansion valve to the underside of the operating diaphragm oi' the valvey by way ol the valve stem 32, so. that while this leakage has substantially no eiiect when the passageway 'I6 isen'tirely unrestricted, it will have an increasingly greater enect as the iiow through the passage 16 is gradually reduced. It should also ne understood that at this time the valve 2.03 isentirelyclosedsothattiierelsno communication between the liquid line 13 and the underside of the operating diaphragm and accordingly the pressure exerted onvthe diaphragm will be some pressure between that existing at the inlet of the evaporator and at the outlet of the evaporator depending upon the adjustment of valve 43 which in turn depends upon the temperature in the space. v

Mountedon the shaft of the motor 202 is a seclonli cam N3' which controls the position -of a mercury switch 2|6 and this cam is, arranged to move the switch 2|6. to closed position whenever the motor 202 has operated the valve 43 to entirely close the passage 16. Accordingly, when the valve 43 has closed entirely and the switch 2 I6 is simultaneously closed the solenoid 20| will be energized as follows: from the line wire 220, through switch 2|B, conductor 22|, solenoid 20| and line wire 222. With the solenoid 20| energized at this time which, it will be understood, will take place only when the space' temperature has` dropped to a desired value, the valvev 200 is opened and accordingly high pressure refrigerant ows to the underside of the operating diaphragm 33 of the expansion valve by way of the -the underside of the operating diaphragm only when positive shut-oli is desired and during the remaining time the diierence between the inlet and outlet pressure of the refrigerant in. the evaporator is made use of to secure proper modulation. v

Referring now to Figure 5, the Valve assembly 33 is shown" as controlling the iiow of liquid re-.

frigerant throughthe pipe i3 to the underside of the operating diaphragm of the expansion valve by way of pipes 230 and 2M.- AThe connection between the underside of the operating diaphragm and the evaporator outlet is provided with a suitable restricting means 2d3 which is illustrated as being adjustable, the adjustment of the orice of the member 243 being effected by `the screw member Zilli. The valve assembly 133 is again illustrated as being operated by an electric proportioning motor as shown in Figure 2 although it should be understood that any suitable operating means for the valve may be utilized. This proportioning motor is controlled 4by the thermostat 205 as in Figure 4 and controls the position of the cam 242 for in turn controlling the adjustment of the valve 43. vA plug 245 may be provided to-close the inlet 6I of the valve assembly since this inlet is not used in this form of the invention.

The arrangement is such that when the space temperature is excessive, as illustrated, the valve '43 will be in closed position thus preventing flow of high pressure refrigerant to the underside of the operating diaphragm of the valve 26 by way of pipes '|3, 240, and 24| so that this diaphragm will respond to the outlet pressure in the evaporator by way of pipe 16, restriction 243, and pipe 24|. As the space temperature starts to fall, the cam 242 will rotate to start opening the valve 43 thus permitting some liquid refrigerant .to flow to the underside of the diaphragm of the expansion valve which thus increases the pressure so that a higher temperature at the bulb 40 is necessary to open the expansion valve' and in this manner the evaporator will contain more'and more superheated refrigerant as the space temperature falls so that a smaller portion thereof is effective for cooling purposes.

When the space temperature has .dropped sufficiently, the valve 43 will be wide open so that a sufficient amount of liquid refrigerant will flow to the space below the expansion valve operating diaphragm to l,maintain the valve tightly closed. It will be apparent that this system is similar in operation to that of Figure 1 but that the valve 43 controls the iiow of the high pressure refrigerant instead of the low pressure refrigerant to the underside of the diaphragm of the expansion valve.

' In many installations vthe pressure drop through the evaporator may be so small that the provision of a connection between the diaphragm of the expansion valve and the outlet of the evaporator coil is entirely unnecessary.v

In such a Icase the pipe 16 may be entirely eliminated 0r the orifice 243 may be adjusted to positively close off the flow through this pipe. In such a case with the valve 43 closed, the operating diaphragm of the valve 26 will respond to the pressure at the inlet of the evaporator which, as stated, may be substantially the same as that of the'outlet pressure and .accordingly the ex- ,pansion valve will operate in accordance with the superheat of the refrigerant leaving the evaporatpr to maintain the coil in a substantially ooded condition. The connection 'i6 however is desirable in installations where the pressure drop through the evaporator is of a considerable value and it is desirable to eliminate this only When the pressure drop is relatively insignicant.

In the various systems described it has been assumed that there is suicient leakage around the stem of the expansion valve to insure that the operating diaphragm thereof will be subjected to the low pressure refrigerant at the inlet of the evaporator. Should an expansion valve be utilized that does not have a suficient leakage around the valve stem then such a passageway may be provided, which may be an external passageway or a suitable passageway provided in the valve body. This connection between the low pressure side of the valvefand the operating dlaphragm is of importance since ,it prevents the pressure below the diaphragm due/to the flow of. liquid refrigerant thereto from the high pressure side of the system from becoming sufficiently great to rupture the operating diaphragm. In the various systems disclosed, the connection between the outlet of the valve 43 :night be made between the expansion valve and the distributor, if a distribution be'employed.

Having described some preferred embodiments of my invention, many modifications will become apparent to those skilled in the art and it should therefore be understood that the invention is limited only by the scope of the appended claims.

I claim as my invention:

1. In a refrigeration system, an evaporator means, means for circulating refrigerant through said evaporator means, thermostatic expansion valve means for controlling the flow of refrigerant through said evaporator means, said expansion valve means including a. pressure responsive operportion of the evaporator means, and means forming a restricted passageway between the high pressure side of the expansion valvemeans and said one side of said operating means.

asoaces 2. In a refrigeration system,` an evaporator means, means for circulating refrigerant through said evaporator means, thermostatic expansion valve means for controlling ,the new of refrigerant through said evaporator' means,'said expansion valve means including a pressure responsive operating means, means providing communication between one side of said operating means and a portion of the evaporator means wherein the pressure is lower than at the inlet side thereof and means providing restricted -com-l munication between said one side oi'said operating means and the inlet of the evaporator means,

valve means' controlling the effectiveness of the 'communication between vthe operating means and the outlet portion of the-evaporator-'meana vsaid evaporator means, thermostatic expansion valve means for controlling the-flow of4 refrigerant through said evaporator means, Said expansion valve means including a pressure responsive operating means, means providing communica.-`

tion between one side of said 'operating means and a portion ofthe evaporator means wherein the pressure is lower than at the inlet side thereof and means providing restricted communication between said oneside of said-operating means and theinlet ofthe evaporator means, valve means controlling the eiectiveness of the communicationbetween the operating means and the outlet portion of the evaporator means, meansv responsive to the temperatureof the medium being cooled by said evaporator means for operating said valve means to reduce the effectiveness of the communication between said-operating means and the outlet portion'of the' evaporator means as the temperature of the medium decreases, and means forming a restricted passagewaybetween the high pressure side of thek expansion valve means and said one side of saidoperating means.

4. In a refrigeration system, an evaporator means, means for circulating refrigerant through said evaporator means, thermostatic eirpansion valve means for controlling the flow of refrigerant through said evaporator means, said expansion valve means including a pressureresponsive operativng means, means .providing communication .between one side of said operating means-and a portion of said evaporator ymeans wherein the pressure is lower than .at the inlet side thereof, means providing communication between said one side of said operating meansv and the highA l pressure side of said expansion valve means, one of said last named means b eing arranged to provide for only a restricted flow therethrough,'and valve means controlling the ilow through the portion of said evaporator means wherein lthe pressure is lower than at the inlet side thereof,

means providing communication between said one sideof said operating means and the high pressure side of said expansion valvemeans, one of said last named means being arrangedto provide for only a restricted flow therethrough, valve means-controlling the iiow through the other of said last named means,I means responsive to a condition being controlled by said evaporator means in control of said valve means, and means forming a restricted passageway between said one forming a passageway between said one side of said operating means and the high pressure side of said expansion valve means, a restriction in said first passageway for permittingonly a limited flow therethrough, a valve in said second passageway for controlling the flow therethrough, and a restricted passageway between said one ,side of said operating means and the low pressure side of said expansion valve means. v

I.'.In a refrigeration "system, an evaporator means, means for circulating refrigerant through said evaporator'means, thermostatic expansion valve means for controlling the flow of refrigerant through said levaporator means, said expansion valve means including a pressure responsive operating means, means forming a passageway between one side of said operating. means and a portion of said evaporator means wherein the pressure is lower than atthe inlet side thereof,

.means forming a passageway between -said one side of said operating means and the high pressure side of said expansion valve means, a valve in said nrst passageway for controlling the flow therethrough, a restriction in said second passageway for permitting only a limited flow therethrough, a restricted passageway between said one side of. said operating means and the`low pressure side of said expansion valve means; and means responsive to a drop in 'temperature of the mediumA vbeing cooled lby said evaporator means for moving the valve in said ilrst passages sion valve means including a vpressure responsive other of said last named means, and-means forming a restricted passageway between said one side of said operating means and the low pressure sidev of said expansion valve means.

5; In a refrigeration system, an evaporatorV means, means for circulating refrigerant through l said evaporator means, thermostatic expansion valve means for controlling the flow of refrigerant through said evaporator means, said expansion valve means including a pressure'responsive operating means, means providingcommunication between one side of said operating means and a side of said operating means and the high presoperating means, means forminga passageway between one side of said operating meansiand a portion of said evaporator means `wherein the pressure is lower than at the -inlet side thereof, means forming a passageway between said one sure side of said expansion valve means, a restriction in said first .passageway for permitting only a limited flow therethrough, a valve in'A said second geway for controlling the now therethrough. a restricted passageway between said one side oi' said .operating means and the low pressure side. of said expansion valvemeans, and means dium being cooled by said evaporator means for moving the valve in said second passageway towards open position.

9. In a refrigeration system, an evaporator means, means for circulating refrigerant through said evaporator means, thermostatic expansion valve means for controlling the flow of refrigerant through said evaporator means, said expansion valve means including a pressure responsive operating means, means forming a passageway between one sideof said operating means and a portion of said evaporator means wherein the pressure is lower than at the inlet side thereof, means forming a passageway between said one side of said operating means and the high pressure side of said expansion valve means, valve means in each of said passageways, and means for opening the valve means in the second of said passageways only when the valve means in the first of said passageways has moved to closed position, and a restricted passageway between said one side of -said operating means and the low pressure side of said expansion valve means.

10. In a refrigeration system, an evaporator means, means for circulating refrigerant through said evaporator means, thermostatic expansion valve means for controlling the ilow ofrefrigerant throughsaid evaporator means, said expansion valve means including a pressure responsive operating means, means forming a passageway between one side of said operating means and a portion of said evaporator means wherein the pressure is lower than at the inlet side thereof, means forming a passageway between said one side of said voperating means and the high pressure side of. said expansion valve means, valve means in each of said passageways, means for opening the valve means in the second of said passageways only when the valve means in the rst of said passageways has moved to closed position, and a restricted passageway between said one side of said operating means and the low pressure side of said expansion valve means, and means responsive to the temperature of the medium being cooled by said evaporator means for moving the valve means in the first of said passageways towards closed position as the temperature of the medium falls.

11,. In a refrigeration system, an evaporator means, means for circulating refrigerant through said evaporator means, thermostatic expansion valve means for controlling the flow of refrigerant through said evaporator means, said expansion valve means including pressure responi vsive means, means subjecting said pressure responsive means to a pressure corresponding to the temperature of the refrigerant in the evaporator means for urging said pressure responsive means in one direction, means forming a pressure charnber wherein the pressure urges said pressure responsive means in the' opposite direction, means providing communication betweensaid chamber and a part of said evaporator means wherein the pressure islower than at the inlet thereof, means providing communication between said chamber and the high pressure side of said expansion valve means, one of said communication means being arranged to provide restricted ilow therethrough, valve means controlling the flow through the other of said communication means, and means providing restricted communication between said chamber and the inlet of the evaporator.

12. In a refrigeration system; in combination;

evaporator means; compressor means for supplying refrigerant thereto and withdrawing it therefrom; a thermostatic expansion valve in control of the flow of refrigerant to the evaporator means and including pressure responsive means operative to move said valve in opening direction with f a force corresponding to the temperature of the refrigerant leaving the evaporator; means interconnecting said pressure responsive means with the evaporator means at a point remote from its inlet end and with the high pressure side'of said system ahead of said expansion valve in such a manner that said pressures act in a direction to close said expansion valve; means, including restricting means and valve means actuated by a psychometric condition of the air being cooled by vsaid evaporator means, for varying the effect of said last named pressures from a value equal to the pressure in the evaporator means at said point of connection to a higher value sufficient to reduce the capacity of said evaporator means by at least thirty percent as the value of said condition changes in a given direction, and to apply high side pressure to said pressure responsive means to positively close said expansion valve when the value of said condition deviates to a predetermined value in the same direction; and means to relieve the high side pressure applied to said pressure responsive means sufficiently to prevent damage thereto while maintaining said pressure high enough to maintain said expansion valve closed.

13. In a refrigeration system, in combination, evaporator means, means for supplying refrigerant thereto including a relatively high pressure source of refrigerant, valve means in control of the iiow'of refrigerant from said source to said evaporator means and including a pressure responsive means, means interconnecting said pressure responsive means with the inlet side of said evaporator means and with a point in said evaporator means remote from said inlet side, means including valve means associated with at least a portion of said connections to determine the pressure applied to said pressure responsive means, a further connection between said pressure responsive means and said high pressure source, and means including valve means for controlling the application of said high pressure to said pressure responsive means.

14. In' a refrigeration system, in combination, evaporator means, means for supplying refrigerant thereto including a relatively high pressure source of refrigerant, valve means in control of the now of refrigerant from said source to said evaporator means and including a pressure responsive means, means interconnecting said pressure responsive means with the inlet side of said evaporator means and with a point in said evaporator means remotev from said inlet side, means including valve means associated with at least a portion of said connections Vto determine the pressure applied to said pressure responsive means, a further connection between said pressure responsive means and said high pressure source, means including valve means for controlling the application of said high `pressure to said pressure responsive means, and means for operating said two last-mentioned valve means in sequence.

ALWIN B. NEWTON. 

